1. Field of the Invention
The present invention relates to a color printer and more particularly, to a color printer with a single photo sensor for detecting the position of an ink ribbon.
2. Description of the Prior Art
Please refer to FIG. 1, FIG. 1 is a perspective view of a ribbon apparatus 10 of a prior art color printer. As shown in FIG. 1, the ribbon apparatus 10 of the color printer comprises an ink ribbon 12, two light sources 32, 52, and two sensors 36, 56. The ink ribbon 12 comprises a plurality of sequentially arranged dye regions 14. Each dye region 14 comprises four dye frames 16, 18, 20, 22 for placing yellow dye, magenta dye, cyan dye, and over coating dye. An opaque dividing section 24 is located between an over coating dye frame 22 and a yellow dye frame 16. An opaque dividing section 27 and a transparent dividing section 26 are installed between the yellow dye frame 16 and a magenta dye frame 18. An opaque dividing section 27 and a transparent dividing section 26 are installed between the magenta dye frame 18 and a cyan dye frame 20. An opaque dividing section 27 and a transparent dividing section 26 are installed between the cyan dye frame 20 and the over coating dye frame 22.
The light sources 32, 52 are located on one side of the ink ribbon 12 for producing light beams 34, 54 with two predetermined colors. The sensors 36, 56, corresponding to the light sources 32, 52, are located on the opposite side of the ink ribbon 12. The sensors 36, 56 are used to detect light beams 34, 54 penetrating through the ink ribbon 12 and produce corresponding signals to determine the position of the ink ribbon. The detection of an opaque dividing section 24 signals the beginning position of a new dye region 14 of the ink ribbon 12, and also corresponds to the beginning position of a yellow dye frame 16. The detection of an opaque dividing section 27 and a transparent dividing section 26 by the sensors 36, 56 corresponds to the beginning position of the magenta dye frame 18, cyan dye frame 20, or over coating dye frame 22. The use of two sets of light sources 26, 28 and sensors 30, 32 for detection of the position of the ink ribbon 12 is a disadvantage of the prior art color printer because it increases the amount of parts used, resulting in higher production costs.
It is therefore a primary objective of the claimed invention to provide a color printer with a single sensor for detecting the position of the ink ribbon for solving the above-mentioned problem.
According to the claimed invention, a color printer with a photo sensor for detecting the position of the ink ribbon is provided. The color printer includes an ink ribbon, a print head, a ribbon-driving device, a controller, and a photo sensor. The ink ribbon includes a plurality of sequentially arranged dye regions. Each dye region includes a plurality of dye frames of different colors. The print head is used to thermally transfer the dye on the ink ribbon onto photo paper. The ribbon-driving device is used to move the ink ribbon in a predetermined direction at a predetermined speed. The print head transfers the dye on each of the dye frames of one dye region onto the photo paper one by one in order to form a color picture. The controller is used to control the operations of the color printer. The photo sensor is used to illuminate the ink ribbon and produce corresponding output signals. The photo sensor outputs a signal of either a first status or a second status. When the controller utilizes the ribbon-driving device to move the ink ribbon in the predetermined direction, a period of time that has passed since the last change in status generated by the photo sensor is used to identify the position of the ink ribbon.
It is an advantage compared to the prior art that the color printer of the claimed invention only needs a single optical sensing system to detect the position of the ink ribbon. The beginning position of each dye frame in the ink ribbon is determined by a digital method, fewer parts are used, and production costs are lowered.
These and other objectives of the claimed invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment, which is illustrated in the multiple figures and drawings.